GitHub user sanjaydasgupta opened a pull request:
https://github.com/apache/zeppelin/pull/2834
[ZEPPELIN-1967] Passing Z variables to Shell and SQL Interpreters
### What is this PR for?
The code in this PR enables embedding/interpolating Z variables into
command strings passed to Spark's SQL and Shell interpreters. It implements the
functionality described in issue
[ZEPPELIN-1967](https://issues.apache.org/jira/browse/ZEPPELIN-1967)
This PR resumes a fresh effort while taking into consideration all of the
discussion in the context of the earlier
[PR-2502](https://github.com/apache/zeppelin/pull/2502). The earlier PR-2502
was closed due to a corruption in my repo that could not be corrected.
The code in this PR resolves all of the discussion and suggestions in the
body of the earlier [PR-2502](https://github.com/apache/zeppelin/pull/2502).
The following description is a summary of the current implementation:
Patterns of the form `{var-name}` within commands will be interpolated only
if a predefined object of the specified name exists in `z`. Additionally, all
such patterns within the command line should also be translatable for any
interpolation to occur. Partial translation of a command line (where only some
of the patterns are translated, and others are not) is never performed.
Patterns of the form `{{any-text}}` are translated into `{any-text}`. This
feature is an escaping mechanism that allows `{` and `}` characters to be
passed into a command without invoking the interpolation mechanism.
The translations described above are performed only when all occurrences of
`{`, `}`, `{{`, and `}}` in any command string conform to one of the two forms
described above. A command that contains `{` and/or `}` characters used in any
other way (than `{var-name}` and `{{any-text}}` as described above) will be
used as-is without attempting any translations whatsoever -- even if the
command also contains legal, translate-able and/or escape-able, constructs of
the above two forms.
No error is flagged in any case. This behavior is identical to the
implementation of a similar feature in
Jupyter's shell invocation using the ! magic command.
At present only the SQL and Shell interpreters support object interpolation.
### What type of PR is it?
[Improvement]
### Todos
* [ ] - Task
### What is the Jira issue?
https://issues.apache.org/jira/browse/ZEPPELIN-1967
### How should this be tested?
A new unit-test class ZeppCtxtVariableTest.java (see below) has been added.
The attached screenshots below also show tests of the functionality.
### Screenshots (if appropriate)
### Questions:
* Does the licenses files need update? No
* Is there breaking changes for older versions? No
* Does this needs documentation? Yes, and detailed documentation has been
added to the part describing ZeppelinContext variables (see file spark.md
below).
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/sanjaydasgupta/zeppelin ZEPPELIN-1967
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/zeppelin/pull/2834.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #2834
----
commit 28688256f3b11e696c08ed10875e0596db8c0463
Author: Sanjay Dasgupta <sanjay.dasgupta@...>
Date: 2018-03-04T07:36:48Z
ZEPPELIN-1967: Initial updates
commit b461c82569e86436239c9d14a8ae38230bc4f357
Author: Sanjay Dasgupta <sanjay.dasgupta@...>
Date: 2018-03-05T02:00:10Z
Merge branch 'master' of https://github.com/apache/zeppelin into
ZEPPELIN-1967
----
---
